Amdromeda

Hints:
A major hint in beating Andromeda is saving your best cards for later, because after Andromeda gets down to 1180 HP, he will transform, and get a whole lot harder.

For the first form, just watch the ground, and when the panel you're on turns yellow, move because a meteor is about to hit there, and you can't block them.
When Andromeda's eyes shine, block, because he's about to launch a rocket (blockable). After about two rounds of missiles, he will nail the whole field with a huge explosion. BLOCK AT ALL COSTS! That attack will hit you with about 200 damage. Continue this, and the first form should be no problem.

As for the second form, he is WAY harder. Instead of just one meteor, Andromeda will now launch three; most of which are aimed at the panel you are standing on. To damage Andromeda, you need to hit the ball in his center, but only when it flashes green, and it only does that when he either is about to attack, or when he just did. Andromeda had 3 main attacks: A huge laser blast to the right, left, or center row. I don't know if it's blockable or not; I just move the heck out of the way! And, he still has the attack that damages the whole field, but now it does about 275 damage! If you just keep using powerful cards after he attacks, you should be able to win.

Main tip: Watch where MegaMan is standing!